John McEnroe turned back the clock today with a virtuoso performance that ousted defending champion Boris Becker from the Australian Open, with McEnroe winning 6-4, 6-3, 7-5.

The unseeded McEnroe, a heavy underdog, electrified a capacity crowd on the 15,000-seat center court stadium with a brilliant exhibition of aggressive tennis that kept the third-seeded Becker defensive and off-balance.Although Becker played well, he couldn't match McEnroe's almost-flawless display of shot-making genius that earned him the victory and advanced him to a fourth-round meeting against No. 13 Emilio Sanchez.

The brash New Yorker brought back memories of his seven Grand Slam titles with an assortment of delicate drop shots, acutely angled cross-courts, nastily spinning serves and stinging passes.

Although Becker had his own very vocal contingent of fans, McEnroe was the darling of the crowd, which cheered on every point before becoming silent instants before each serve.

Making his first appearance here since he was defaulted two years ago for a temper tantrum, McEnroe's behavior was immaculate. Instead, it was Becker who became irate over line calls, particularly in the second set when he complained bitterly several times to the umpire.

Earlier in the day, top seeds Stefan Edberg and Monica Seles won easily.

Seles, apparently recovered from her strained neck, breezed to a 6-1, 6-1 third-round blitz of Yayuk Basuk of Indonesia.

Edberg got a tougher workout, bouncing back from service breaks early in the first and third sets to oust Australian John Fitzgerald 7-5, 6-1, 6-4.

John McEnroe's younger brother, Patrick, was beaten by Andrei Chesnokov 6-4, 1-6, 1-6, 6-1, 6-3 with the Russian making a big comeback after being on the brink of elimination.

Ivan Lendl, a two-time champion and seeded No. 5, overcame the service blasts of 6-foot-5 German Markus Zoecke to win 6-4, 6-4, 7-6 (8-6).

David Wheaton, the No. 15 seed and winner of $2 million at the Grand Slam Cup last month, cruised past Lars Koslowski 6-4, 6-3, 6-3.

But no one put on a show like John McEnroe, and what a show it was.

On a chilly night that had fans bundled up in coats and blankets, McEnroe - his right knee wrapped in a red-and-black elastic wrap and his head covered by a white baseball cap - had no trouble warming up.

He came out firing, making it clear from the start he was going for broke. He followed his first serve in constantly and often took advantage of Becker's second serve to do the same.

Becker succumbed in the 11th game of the final set after five break points. When Becker, who fended off three break points in his previous service game, hit a backhand long for the break, McEnroe pumped both fists, and the crowd roared, sensing the upset in the making.

McEnroe served successive aces, his fifth and sixth of the match, to go to match point at 40-30, then watched Becker's last shot, a backhand, float long for the final point.

McEnroe raised both arms to the crowd and flashed the most satisfied smile he had shown in a long time, then whacked a ball high into the stands after shaking Becker's hand at the net. McEnroe again pumped his arms in the air as the crowd's cheers intensified.

Becker, who had eight aces but none in the first set, never could raise his game to the level he has shown in the past. Rather, he stomped around the court, angrily berating himself as he did when he lost the Wimbledon final to Michael Stich last year.

"Nothing goes!" Becker screamed in German at one point. "Trash, Trash!" he yelled on another occasion.

Once he even offered a lineswoman his racket early in the third set, asking if she wanted to play for him. Becker, who reached the No. 1 ranking for the first time in his career after winning here last year, could leave this time as low as No. 7.

McEnroe played better than he has since perhaps the 1984 U.S. Open, his fourth and last at Flushing Meadow. That year, he also won Wimbledon and was ranked No. 1 for the last time.

McEnroe missed the Australian Open last year with a shoulder injury, lost in the first round at the French, the fourth at Wimbledon and the third at the U.S. Open as he finished the year ranked 28th, the worst since he turned pro in 1978.

McEnroe played so fluidly that in one stretch, he lost only four points in four service games from the end of the first set to the middle of the second.

Rather than relying only on touch volleys and finesse, McEnroe matched Becker's power with plenty of his own as he put away approach shots and backpedaling overheads.